May 29 (UPI) -- Experts said a suspected earthquake that rattled portions of South Carolina was actually a sonic boom of unknown origins. The U.S. Geological Survey confirmed the incident just before 5:30 p.m. Thursday was not an earthquake, but a sonic boom estimated to have originated in the St. Andrews area before traveling across multiple counties, including the Columbia area and the Midlands. The Geological Survey said its equipment is not calibrated to measure sonic booms, so the event